Retractable and extensible roof assembly



May 31, 1966 R. J. DEISENROTH RETRACTABLE AND EXTENSIBLE ROOF ASSEMBLYFiled Sept. 4, 1965 4 Sheets-Sheet 1 IN VENTOR ATTORNEY ROBERT J.DEISEWROTH' y 1966 R. J. DEISENROTH 3,253,857

RETRACTABLE AND EXTENSIBLE ROOF ASSEMBLY INVENTOR ROBERT J OE/SE/VROTHBY fi waf ATTORNEY May 31, 1966 R. J. DEISENROTH RETRACTABLE ANDEXTENSIBLE ROOF ASSEMBLY Filed Sept. 4, 1963 4 Sheets-Sheet 5 INVENTORROBERT J DEISEWROTH iii ATTORNEY May 31, 1966 R. J- DEISENROTHRETRACTABLE AND EXTENSIBLE ROOF ASSEMBLY 4 Sheets-Sheet 4 Filed Sept. 4,1963 INVENTOR ROBERT J. 05785 IVROT' H ATTORNEY United States Patent3,253,857 RETRACTABLE AND EXTENSIBLE ROOF ASSEMBLY Robert J. Deisenroth,Elkhart, Ind., assignor to Excel This invention relates to vehicularroof assemblies and particularly to roof assemblies which may beextended and retracted to increase, at will, vehicular head space orhead room. More particularly, the invention relates to new and improvedextensible and retractable roof assemblies for vehicles which have newand improved design features over those of the prior art. Still moreparticularly, the invention relates to new and improved weatherproofextensible and retractable vehicular roof structures which are usefulfor varying vehicular head room.

The concept of extensible and retractable roof assemblies for motorvehicles, trailers, boat super-structures, and the like is known. Theprior art has recently taught the concept of a vehicular roof assemblywhich is so designed to increase head space or head room when theoccupants desire; however, the art is still in its infancy and acompletely satisfactory roof assembly having the features andcharacteristics desired as the ultimate is not yet available eithercommercially or, so far as is known, in the research stage. One patenton a collapsible roof assembly is US. Patent No. 2,926,042 issuedFebruary 23, 1960, to M, Calthorpe.

The roof assembly concept to which the instant invention is directedinculcates design features which permit the assembly to be retractedduring vehicular motion so that a fiat low silhouette and the resultantlow wind resistance is experienced. At the same time, when vehicularmotion is stopped, the assembly may be extended in order to permit easeof movement within the vehicular area because of the increased headroom. Generally the extended roof assembly presents an arcuate roof linewith the center or chord of the arch at the middle of the assembly andwith the arcuate roof portion being supported by side panels which arealso arcuate along the top edge thereof, said arcuate edges maintainingline contact with the roof in its extended position. The arcuate sidepanels are hingedly secured so as to retract by rotating inwardly andthe roof portion, which is of a flexible material, is allowed to lowerand lock in the general plane of the vehicular roof.

It will be appreciated that such a roof assembly, in order to beacceptable, must be of such design to keep out the wind and rain sinceit normally forms a part of weather tight vehicular structure. It willalso be appreciated that the problems of weatherproofing such a movablestructure are diflicult and a great deal of attention has been given tothese problems.

The instant invention is directed toward a roof assembly that isextensible and retractable and which includes new and novel features ofdesign and structure which make it substantially completely waterproofboth in its extended and retracted position.

Brieflythe roof assembly of the instant invention comprises a frame, aflexible roof, two arcuate side panels rotatably attached to said frame,and an adjusting member attached to said frame which allows the assemblyto be fitted to vehicular roof surfaces of different shapes and slopes.The roof, which is of a flexible material, is pivotally attached at therear end thereof to said frame and slidably attached to the frame at theforward or front end thereof.

i The roof assembly of the invention is 'normally mounted on a vehicularroof which has a rectangular opening therein of a size just slightlysmaller than the outline of the frame of the assembly. The frame ispermanently affixed to the vehicular roof by means hereinafter describedand the juncture between the assembly and the vehicular roof is coveredby a garnish or surround to present an esthetic appearance thereto. Theassembly of the invention is so designed that when the side panels areretracted and the roof member assumes the plane of the vehicular roof,it is locked in this position and a low flat silhouette is presented forvehicular motion. The improved design to be described more in detailbelow renders the assembly substantially completely waterproof in thisretracted position as well as when extended.

As has been mentioned above, one of the problems with the extendabletops of the prior art has been that of the sealing means employed toweatherproof the assembly, particularly when the vehicle is moving. Oneof the features of the improved extendable top of the instant inventionis the sealing means employed to solve the weatherproofing problemswhich have presented themselves to the art.

Generally speaking, the improved assembly to which this invention isdirected comprises a rectangular frame which is supported directly by avehicular roof, a flexible top which is slidably fastened to the frameat the front end thereof and rotatably fastened to the frame at the rearend thereof, and two side panels, arcuate in shape, which are rotatablyfastened to the sides of said rectangular frame. When extended, the sidepanels are in vertical relation to the plane of the frame and theflexible top is positioned along the arcuate edges of the side panelsforming a curved roof line when viewed from a side. When retracted, orlowered, the side panels rotate inwa'rdly about their point ofattachment to the frame until they lie in a plane parallel to the frameand the top retracts downwardly, the rear end rotating about its pointof attachment to the frame and the front end slidably adjusting at itspoint of slidable attachment until the complete top is resting in aplane which is also parallel to the rectangular frame and is makingcontact with an angled portion of each of the side panels.

- The inventive concept will be more clearly explained by reference tothe drawings in which:

FIG. 1 represents a perspective view of the retractable and extensibletop of the invention in its lowered position;

FIG. 2 is a perspective view of the top in its raised position;

FIG. 3 is a section taken along the line 33 of FIG. 1;

FIG. 4 is a section taken along the line 4-4 of FIG. 2;

FIG. 5 is a section taken along the line 55 of FIG. 1;

FIG. 6 is a section taken along the line 6-6 of FIG. 2;

FIG. 7 is a side elevation showing the top of the invention in itsraised or extended position;

FIG. 8 is a section taken along the line 8-8 of FIG. 7;

FIG. 9 is a side view of the locking assembly which locks the top inposition in its retracted attitude;

FIG. 10 is a cross-sectional view of the hinge means by which the roofportion is attached to the frame member in the rear of the assembly;

FIG. 11 is a sectional view through the roof assembly illustrating thecleat structure for locking the unit in theangle. The H-beam member isformed by a rolling or stamping process from one sheet of material andhas an inside and outside upper and lower flange. The strip 12 isattached to the lower flange by means of rivets 17. The top member 14 ofthe vehicular roof is rolled upwardly and outwardly and is permanentlyaffixed to strip 12 by means of rivets 16. An elastomeric sealingcompound is normally placed between roof member 14 and strip 12 prior toriveting, thus assuring a completely weatherproof juncture at thiscritical point of attachment. It will be noted that the strip 12 extendsfor the length of the H-bearn and downwardly therefrom to the surface ofthe vehicle roof. The contour of the lower edge of the strip 12 may beconfigured to mate with the contour of any vehicle roof surface on whichthe top assembly is mounted.

The short sides of the frame, that is the front and rear sides thereof,comprise a cross-member 17 which is adapted to be permanently affixed tosaid H-beam members 10 which comprise the long sides of the frame. Thepoint of attachment to the H-beam is shown at 19 of FIG. 12 and may beaccomplished by spot-welding, riveting, etc. The cross, member isaffixed to both upper flanges of the H-beam member, and thus the sideH-beam members with the two cross members form a rigid rectangular framefor the assembly of the invention.

A garnish member, or surround, which comprises an angled sheet ofmaterial, is applied to the inside surface of the vehicular roof and tothe inside lower flange of the H-beam member. This garnish, shown at 18,is fixedly secured to the inside bottom flange of the H-beam by rivet 20and is of such a design that the angle at 18a is increased uponinstallation, thus holding the end 18b tightly against the vehicularroof. The tension exerted by this design thus prevents any chatter, orrubbing and adds to the tightness of the assembly. The garnish serves topresent a pleasing appearance from the inside of the vehicle andpresents a mounting surface for accessories such as lights, fans, etc.

Rotatably secured to the top inner flange of the H- beam by means ofplastic hinges shown at 22, is side panel 24. Detail of the side panelis shown in the lowered position in FIGS. 3 and and its raised positionin FIGS. 4 and 6. It will be noted that the bottom portion of side panel24, or portion 26, is fashioned at a right angle to the main section ofthe side panel 24 and in its lowered or retracted position, as shown inFIGS. 3 and 5 forms a support for the roof assembly, the point ofsupport comprising an elastomeric sealing strip shown at 28 which formsa weatherproof seal with the roof portion when in contact therewith.When the side panels are in raised or elevated position, sealing strip28 forms a weatherproof seal with the middle section of the H- beam asshown in FIGS. 4 and 6. Sealing strip 28 is of an extruded or moldedplastic material and is of a U-shaped cross-section having an upwardlyextending flexible tip. This strip forms a weather-tight seal along thelength of the H-beam.

The improved travel-top assembly of this invention has as anotheroutstanding feature the unique roof design which is shown incross-section in FIGS. 3 through 6-. Basically, the roof comprises asheet of flexible material illustrated at 30. Its width is suflicient tobring its edges at approximately the middle of the H-beam of the sideframe members. Its edges terminate in an elastomeric weather strip ofunique design. This weather stripping material, or sealant strip, shownat 32, comprises a rectangular strip of extruded plastic material whichhas as an integral portion thereof an inwardly inclining lip or tongue.The weather stripping material is adhesively attached along the edgeline of the roof. When the roof is in the lowered position, as shown inFIGS. 3 and 5, the unique design of the strip prevents wind and rainfrom penetrating the seal between roof member 30 and sealing strip 28 onangle 26 of side member 24. When the Cleat members 35 extend throughthese support members 34 and roof member 30 and are more completelydescribed below.

On the inner surface of room member 30* there is positioned a series ofparallel ribs which extend across the inner surface of roof 30. Theserib members may be embossed directly from the material of the roof bydrawing, etc. or they may be constructed separately and affixed to theroof member 30 by spot-welding and the like. The rib members serveseveral useful purposes. They add strength to the roof member 30. Theyform sliding surfaces for support of the roof by the arcuate portion ofthe side panels during the roof raising or elevating operation and thusprevent marring or scratching of the under surface of roof member 30.The point of their termination toward the edge of roof member 30 forms alocking situation for maintenance of side panels in vertical relation.One such rib member is shown at 36 with the angular end portion shown at38 in FIGS. 3 and 4.

As was mentioned above, the weatherproofing of the juncture of the roofand side panels, both when in raised or lowered position, is animportant feature of the improved assembly of this invention. When inlowered or retracted position, the 'H-beam construction of the sideframe members in conjunction with the sealing strip 28 on the bottom ofside panels 24 and with sealing strip 32 on the edges of the roof formsa substantially completely weatherproof juncture. When side panel 24 isin the elevated position, the seal between roof member 30 and the top ofthe side panel is extremely important and is shown in detail in FIGS. 4and 6. Side panel 24 terminates at its top portion in an outwardlyextending right angled bend shown at 40. This angular portion is coveredby a sealing strip 42 which extends completely over the outer surface ofangular bend 40 and is attached thereto. This sealing strip is preparedfrom a plastic material which has a waxy, smooth surface with a lowco-eflicient of friction so that it will slide easily when in contactwith rib members 36 during extending and retracting operations. Whenside member 24 is elevated to be placed in its vertical position, roofmember 30 is raised by the angular action of the arcuate portion of sidepanel 24, sealing strip 42 being in direct contact with rib members 36.In this vertical position sealing strip 42 makes contact with sealingstrip 32 and is held in contact by the locking situation afforded by theends 38 of rib member 36 and angle 40. The combination of the contactbetween sealing strip 42 and roof member 30 together with the shelteringaction of the tongue or lip of sealing strip 32, insures a completelywaterproof seal between the roof and the elevated side panel of theassembly of the instant invention.

Between the hinge members, side weatherproofing is accomplished bysealing strips 44 as is shown in FIG. 5 and FIG. 6, which arecross-sectional views taken along the lines 5-5 of FIG. 1 and 66 of FIG.2 respectively. When side panel 24 is in its retracted position contactis madebetween sealing strip 44 and the side panels so as to insure thatno wind or moisture penetrates the interior. Sealing strip 44 is similarin shape and is of the same dimensions as sealing strip 28 and whenadhered securely to the shorter inside flange of the H-beam it surroundsa double thickness and thus no bulging of the sides is experienced.

At the front end of the top assembly there appears cover plate 46.Beneath this cover plate and afiixed to each side frame member ischannel member 48 which is adapted to receive nylon rollers 50 which arefitted to the ends of cross rod 52. Rod 52 is permanently aflix'ed toroof 30 and the assembly comprises the slidable attachment referred toabove which attaches roof member 30 to the frame assembly. The positionof roller member 50 in channel member 48 when the roof is in theelevated position is shown in phantom in FIG. 7. As the roof isretracted roller member 50 slides forward and upward to accommodate theroller member 50 in the completely retracted position of the roof asshown in FIG. 1.

The pivotal attachment of the rear end of roof member 30 to the framemember is shown in FIG. 10. Hinge member 54 is attached to rear crossmember 17 by rivetting, welding, or other fastening means. Pivoting pin56 which is attached to pin plate 58 which in turn is securely afiixedto roof member 30 pivots within hinge member 54 as the roof is elevatedand retracted. FIG. shows these details with the solid line representingthe elevated position and the dotted lines showing the retracted orlowered position.

When in the lowered or retracted position, roof 30 is held in horizontalrelation by means of eccentric lock assembly 60, cooperating in knownfashion with locking attachment 62. The lock assembly 60 is attached tothe front cross member 17 by means of fastening device 64.Weatherproofing at this juncture is provided by means of sealing strip68 which includes an integral projection shown at 70. Sealant strip 68is permanently aflixed to the top of cross member 17 and projection 70makes line contact with roof member 30 the width of the roof. At eachend of cross member 17 there is attached a sponge rubber block 66 tomake weatherproof contact with sealing strip 28 of side panel 24 andsealing strip 32 of roof member 30.

When in its retracted or lowered position roof 30 is supported at therear thereof by the hinge means shown in FIG. 10, at the front endthereof by means of the slidable fastening means shown in FIG. 8 andalong the sides thereof by the angular portion 26 of side members 24,direct contact being made with sealing strip 28. It is locked in thisposition by the lock assembly shown in FIG. 9. The side members 24, whenlowered, are held in horizontal position by means of cleats 35. Thesecleat members are attached through roof member 30 and rib members 34 bymeans of screws as shown at 72 of FIG. 11. Cleat member 35 is preferablyof metal and covered with a vinyl covering as is shown at 74. As theroof is retracted and side panel members are rotating inwardly abouthinge members 22 they are firmly held by the conformation of cleat 35 asshown in FIG. 11. Thus any possibility of vibration or rattling isremoved when the roof is locked in its retracted position. It will benoted that each cleat member 35 comprises a downwardly depending portion76 having oppositely disposed inwardly curved surfaces 78, 80. Theportion 76 terminates in a neck 82 which has outwardly curved surfaces84, 86 which merge into the horizontally extending surfaces 88, 90 ofoutwardly directed fingers 92, 94. The structure thus described definesa pair of oppositely disposed recesses to receive the bent portions 40of the side panels 24 when the side panels are pivoted into thehorizontal plane. The cleats, which are positioned in the center of theroof members 30, receive the portions 40 of the side panels 24 as theroof member is lowered and the side panels are pivoted downwardly. Thecurvature of surfaces 78, 80 serves to guide and firmly seat th portions40 into place to prevent rattling.

To summarize briefly the instant invention is an improved extensible andretractable roof assembly which is completely weatherproof and which,because of its unique construction and many novel features, representsan advance over the existing art. It comprises a frame, a flexible roofwhich is pivotally attached at the rear thereof to said frame andslidably attached to said frame at the front end, arcuate side panelswhich are rotatably attached to side frame members, and an adjustingmember which is attached to the underside of said frame member and whichallows the assembly to be adapted to roof surfaces of different shapesand slopes.

The frame member comprises a novel H-beam construc tion in which theside frame members are fixedly attached to said cross frame members. TheH-bearn is constructed of one piece of material and has a longer outsideflange and a shorter inside flange. The side panel members areconstructed so that the bottom and top portions thereof are turnedoutwardly at a right angle and the outside edge of the bottom angledportion is covered with a sealing strip of extruded plastic having aflexible tip thereon. The outside edge and end of the top angled portionof the side assembly is also covered with a plastic sealing strip. Theinside upper flange of the side frame assembly is covered with a plasticstrip having a flexible tip thereto which is similar to the one coveringthe outside edge of the bottom angled portion of the side panel. Theside arcuate panels are rotatably secured to the inside upper flange ofthe side frame assembly by means of plastic hinges. The outside edge ofthe flexible roof assembly is covered by an extruded plastic strip whichcomprises a rectangular cross-section having an incross members rigidlyaffixed at the ends of said members,

a flexible top of a sheet of pliable material, said top being pivotallyattached at one end to said frame and slidably I attached at the otherend to said frame, said top being movable to a raised position and alowered position, a pair of arcuate side panels each being pivotallyattached and sealed to the upper edge of the inner wall of one of theH-beams, said side panels being pivotal to a raised position wherein thefree edges thereof form a sealed juncture with the top, said side panelsbeing pivotal to a lowered position, and extension means on thepivotally attached edges of the side panels, said extension meansforming a sealed juncture with the top when the panels are in a loweredposition, said extension means being received in the channel defined bythe H-beam when the side panels are in the raised position.

2. A weatherproof top assembly according to claim 1 and furthercharacterized in the provision of an extruded rectangular plastic stripon each side edge of the flexible top and extending for the lengththereof, each plastic strip having an inwardly inclining downwardlyextending lip portion extending the length thereof, said lip portionextending beneath the sealed juncture of the side panels with the top inboth the lowered and raised position to shield the sealed junctures fromthe weather.

3. An extensible and retractable weatherproof top assembly for mountingon the top of vehicles having different top surface configurationcomprising a frame having side members of H-bea-m construction with theouter and inner walls thereof extending generally upwardly, front andrear cross members rigidly aflixed at the ends of said side members, andstrips attached to the outer surface of the outer wall of each H-beamand extending for the length thereof, each strip extending downwardlybeyond the'lower edge of the outer H-beam wall, the lower edge of eachstrip being contoured to mate with the contour of the vehicle roofsurface, a flexible top of a sheet of pliable material, said top beingpivotally attached at one end to said frame and slidably attached at theother end of said frame, said topbeing movable to a raised position anda lowered position, a pair of arcuate side panels each being pivotallyattached and sealed to the upper edge of the inner wall. of one of theH-beams,'said side panels being pivotal to a raised position wherein thefree edges thereof form a sealed juncture with said flexible top, saidside panels being pivotal to a lowered position, extension means on thepivotally attached edges of the side panels, said extension meansforming a sealed juncture with the top when the panels are in a loweredposition, said extension means being received in the channel defined bythe H-beam when the side panels are in the raised position.

4. An extensible and retractable weatherproof top assembly comprising aframe having side members of H-beam construction with the outer andinner walls thereof extending generally upwardly, front and rear crossmembers rigidly affixed at the ends of said side members, a flexible topof a sheet of pliable material, said top being pivotally attached at oneend to said frame and slidably attached at the other end to said frame,said top being movable to a raised position and a lowered position, apair of arcuate side panels, a plurality of spaced apartfluid-impervious plastic hinges pivotally attaching each of the sidepanels to the upper edge of the inner wall of one of the H-beams, anextruded plastic sealant strip of U-shaped conformation extending alongthe length of the upper edge of each of the inner walls of the H-beam onthe edge portions not covered by the plastic hinges, the sealant striphaving an upwardly extending flexible tip portion as an integral partthereof for sealing engagement with the side panels when said sidepanels are pivoted to a lowered position, said side panels being pivotalto a raised position wherein the free edges thereof form a sealedjuncture with the top, said side panels being pivotal to a loweredposition and having sealing means thereon forming a sealed juncture withthe top when the panels are in a lowered position.

5. An extensible and retractable weatherproof top assembly comprising aframe having side members of H-beam construction with the outer andinner walls thereof extending generally upwardly, front and rear crossmembers rigidly affixed at the ends of said side members, a flexible topof a sheet of pliable material, said top being pivotally attached at oneend to said frame and slidably attached at the other end to said frame,said top being movable to a raised position and a lowered position, apair of arcuate side panels each being pivotally attached and sealed atone edge to the inner wall of one of the H-beams, said side panels beingpivotal to a raised position wherein the free edges thereof form asealed juncture with the top, said flexible top having a plurality ofspaced apart rib members on the underside thereof extending across themajor portion of the top and terminating short of the edges thereof, andmeans at the edges of the top defining with the ends of the ribs arecess for receiving therein the free edges of the arcuate side panelsand locking said arcuateside panels in their vertical position, saidside panels being pivotal to a lowered position, and sealing means onthe side panels forming a sealed juncture with the top when the panelsare in a lowered position.

6. A weatherproof top assembly according to claim and furthercharacterized in that said arcuate side panel has an outwardly extendingangled portion as an integral part of the top edge thereof, the outsideedge and the top of said outwardly extending angled portion beingcovered with a plastic sealant strip having a low coefficient offriction for easy sliding across the ribs and for sealing engagementwith said recesses.

7. An extensible and retractable weatherproof top assembly comprising aframe having side members of H-beam construction with the outer andinner walls thereof extending generally upwardly, front and rear crossmembers rigidly afiixed at the ends of said side members, a flexible topof a sheet of pliable material, said top being pivotally attached at oneend to said frame and slidably attached at the other end to said frame,said top being movable to a raised position and a lowered position, apair of arcuate side panels each being pivotally attached and sealed tothe upper edge of the inner wall of one of the H-beams, said side panelsbeing pivotal to a raised position wherein the free edges thereof form asealed juncture with the top, said side panels being pivotal to alowered position, extension means on the pivotally attached edges of theside panels, said extension means carrying an extruded plastic sealantstrip of U-shaped conformation having an outwardly extending flexibletip portion forming a sealed juncture with the top when the panels arein a lowered position, said extension means being received in thechannel defined by the H-beam when the side panels are in the raisedposition.

8. An extensible and retractable weatherproof top assembly comprising aframe having side members of H-beam construction with the outer andinner walls thereof extending generally upwardly, front and rear crossmembers rigidly aflixed at the ends of said side members, a flexible topof a sheet of pliable material, said top being pivotally attached at oneend to said frame and slidably attached at the other end to said frame,said top being movable to a raised position and a lowered position, apair of arcuate side panels each being pivotally attached and sealed atone edgeto the inner wall of one of the H-beams, said side panels beingpivotal to a raised position wherein the free edges thereof form asealed juncture with the top, said side panels being pivotal to alowered position, cleat members on the underside of said top, each cleatmember having a pair of oppositely disposed recesses with curvedsurfaces, said cleat members having a resilient coating thereon, eachrecess of each cleat member receiving a marginal portion of the upperedge of one of the side panels when the side panels are pivoted to alowered position to firmly seat the side panels in the lowered position,an extension on the pivotally attached edges of the side panels, saidextension forming -a sealed juncture with the top when the panels are inthe lowered position.

References Cited by the Examiner UNITED STATES PATENTS 1,416,112 5/1922Miles 2969l 1,963,941 6/1934 Duffy 189--46 X 2,664,309 12/1953 Kavalar296-107 X 2,903,298 9/1959 Stahl 296-137 2,926,042 2/1960 Calthorpe296137 2,954,999 10/1960 Fingerman et al 296107 3,014,753 12/1961Nagetusch 29623 3,019,486 2/1962 Stinson' 16138 3,075,234 1/1963Speakman 2016 X 3,134,198 5/1964 Calthorpe 296137 X FOREIGN PATENTS382,446 10/1932 Great Britain.

BENJAMIN HERSH, Primary Examiner.

A. HARRY LEVY, PHILIP ARNOLD, Examiners.

C. C. PARSONS, Assistant Examiner.

1. AN EXTENSIBLE AND RETRACTABLE WEATHERPROOF TOP ASSEMBLY COMPRISING AFRAME HAVING SIDE MEMBERS OF H-BEAM CONSTRUCTION WITH THE OUTER ANDINNER WALLS THEREOF EXTENDING GENERALLY UPWARDLY, FRONT AND REAR CROSSMEMBERS RIGIDLY AFFIXED AT THE ENDS OF SAID MEMBERS, A FLEXIBLE TOP OF ASHEET OF PLIABLE MATERIAL, SAID TOP BEING PIVOTALLY ATTACHED AT ONE ENDTO SAID FRAME AND SLIDABLY ATTACHED TO THE OTHER END TO SAID FRAME, SAIDTOP BEING MOVABLE TO A RAISED POSITION AND A LOWERED POSITION, A PAIR OFARCUATE SIDE PANELS EACH BEING PIVOTALLY ATTACTED AND SEALED TO THEUPPER EDGE OF THE INNER WALL OF ONE OF THE H-BEAMS, SAID SIDE PANELSBEING PIVOTAL TO A RAISED POSITION WHEREIN THE FREE EDGES THEREOF FORM ASEALED JUNCTURE WITH THE TOP, SAID SIDE PANELS BEING PIVOTAL TO ALOWERED POSITION, AND EXTENSION MEANS ON THE PIVOTALLY ATTACHED EDGES OFTHE SIDE PANELS, SAID EXTENSION MEANS FORMING A SEALED JUNCTURE WITH THETOP WHEN THE PANELS ARE IN A LOWERED POSITION, SAID EXTENSION MEANSBEING RECEIVED IN THE CHANNEL DEFINED BY THE H-BEAM WHEN THE SIDESPANELS ARE IN THE RAISED POSITION.